Substrate and Inhibitor Spectra of Ethylbenzene Dehydrogenase: Perspectives on Application Potential and Catalytic Mechanism
Substrate and Inhibitor Spectra of Ethylbenzene Dehydrogenase: Perspectives on Application Potential and Catalytic Mechanism
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DOI：
10.1128/aem.01551-12
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发表时间：
2012-09-01
影响因子：
4.4
通讯作者：
Heider, Johann
中科院分区：
文献类型：
--
作者：
Knack, Daniel;Hagel, Corina;Heider, Johann
乙苯脱氢酶（EbDH）催化反硝化菌厌氧降解乙苯的第一步，即乙苯不依赖氧的羟基化反应生成(S)-1-苯乙醇。在我们的研究中，我们研究了46种底物类似物作为酶的底物或抑制剂的动力学性质。这些化合物的表观动力学参数为了解酶的功能提供了重要的见解，并且与基于量子化学计算模型的预测催化机制一致。特别是，某些底物形成脱氢和羟基化的替代产物证实了所提出的底物衍生的自由基和碳正离子中间体的存在，这可以被视为机理模型。此外，这些结果还表明，EbDH在将不同种类的烷基芳和杂环化合物羟基化成相应的醇方面具有惊人的高度多样性。这可能导致乙苯脱氢酶有吸引力的工业应用，用于通过相应芳香烃的羟基化而不是减少相应酮的习惯程序来生产醇的新工艺。
Ethylbenzene dehydrogenase (EbDH) catalyzes the initial step in anaerobic degradation of ethylbenzene in denitrifying bacteria, namely, the oxygen-independent hydroxylation of ethylbenzene to (S)-1-phenylethanol. In our study we investigate the kinetic properties of 46 substrate analogs acting as substrates or inhibitors of the enzyme. The apparent kinetic parameters of these compounds give important insights into the function of the enzyme and are consistent with the predicted catalytic mechanism based on a quantum chemical calculation model. In particular, the existence of the proposed substrate-derived radical and carbocation intermediates is substantiated by the formation of alternative dehydrogenated and hydroxylated products from some substrates, which can be regarded as mechanistic models. In addition, these results also show the surprisingly high diversity of EbDH in hydroxylating different kinds of alkylaromatic and heterocyclic compounds to the respective alcohols. This may lead to attractive industrial applications of ethylbenzene dehydrogenase for a new process of producing alcohols via hydroxylation of the corresponding aromatic hydrocarbons rather than the customary procedure of reducing the corresponding ketones.